The so-called “heavy landing” or “hard landing” indicates a landing event in which speed or acceleration speed of the aircraft in vertical direction is above respective limit value when landing, wherein heavy landing means that vertical speed or acceleration speed of the aircraft is above respective limit value when landing in case that the landing weight of the aircraft is above the maximum landing weight, and hard landing means that vertical speed or acceleration speed of the aircraft is above respective limit value when landing in case that the landing weight of the aircraft is less than or equal to the maximum landing weight. The hard/heavy landing can impose strong impact and vibration on the structure of the aircraft, particularly the components withstanding greater loads such as the wing, landing gear, engine and the like, and cause failure of the structure of the aircraft. Therefore, the airline must perform a strict safety-check on the aircraft to ensure aviation safety once the hard/heavy landing occurs.
Different aircrafts have different limit values. For example, the limit value of vertical landing acceleration speed of Boeing B747-400 is 1.7 G, the limit value of vertical landing acceleration speed of Boeing B737-600 is 2.1 G, and the limit value of vertical landing acceleration speed of Airbus A320 is 2.6 G.
According to provisions of aircraft manufacturer, the subject of liability for reporting the happened hard/heavy landing event is the flight crew. However, the hard/heavy landing event reported by the flight crew has great uncertainty. The final results of most hard/heavy landing events reported by the flight crew are “the hard/heavy landing has not occurred”. But the processing causes an interruption of service of the aircraft and a big waste of maintenance resource.
Over-limit data statistics and trend analysis, which are useful for eliminating hidden dangers and ensuring the safety, can be obtained through decoding the data in the QAR (Quick Access Recorder). However, it can often be found that there exist large differences between the result of decoding the data in the QAR and the actual situation when analyzing the hard or heavy landing event. Therefore, the data obtained from QAR decoding cannot directly be used to determine the hard/heavy landing event.
The airframe structure message of the aircraft also can be used to determine the hard or heavy landing event. The airframe structure message is one kind of aircraft system message and is automatically generated by the aircraft data system. However, it is found in practical applications that in many cases the aircraft system does not generate the airframe structure message although the flight crew has reported the hard or heavy landing event. Therefore, the airframe structure message cannot directly be used to determine the hard or heavy landing event, either.
Therefore, repairmen have to provide the original flight data to the aircraft manufacturer for analysis once the flight crew reports the hard or heavy landing event according to conventional technique. Such manner is not only expensive but also time-consuming and influences the aircraft's normal flight.